https://issues.dlang.org/show_bug.cgi?id=23178

          Issue ID: 23178
           Summary: Unknown error using alias to `__traits` evaluated as
                    expression
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody@puremagic.com
          Reporter: boris2.9@gmail.com

On master, test:

alias a = __traits(isIntegral, 1.1);
pragma(msg, a);

Output:
Error: unknown, please file report on issues.dlang.org
test.d(2):        while evaluating `pragma(msg, a)`

It should print 'can't alias expression...'

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